Method of electric thermal control



M. H. SHOENBERb.

METHOD OF ELECTRIC THERMAL CONTROL.

APPLICATION FILED DEC.27,1919.

7 1,393,323, Patented Oct. 11, 1921.

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i To all may concern.

Be it known that -I, MILTON H. SHOEN- BERG, a citizen of'the- UnitedStates, and a resident of the cit and county of, San Francisco, State ofalifornia, have invented new and useful Improvements in Methods ofElectric Thermal Control, of which the following is a specification;

My invention has for its principal ob ect the control of terminalelectrical apparatus 'in which current consumption is utilized inovercoming resistance, as in heaters, motor clrcults and the like, andconsists of the method by which the flowing current is switch in mco-pending zt' No. 347,732 and Serial 3 the operating as -for exampDecember 27, 1919, whereby automatically tripped and automaticallysnapped into its open position, thereby cutting out the terminal circuitfrom the re mote device.

. By referringto the accompanying draw-' my invention will be madeclear. l he figure illustrates my method as applied to a water heater,bath; is to be understood that it is equally applicable to any otherform of apparatus in which a variaheater coil 4, ada

"nected to the su tion'in temperature will occur, or may be caused tooccur in an ex ansible element.

A water heater is in icated by numeral 1, provided with an inlet at 2,and anoutlet at 3, and having an electrical resistance pted to beenergized through the connections 5 and 6. The latter is in electricalconnection with the metallic support 7, which is cut away at 8 toprovide read "accessfifor circulating water to,and heat dissipationfrom, the expansible wire 9. This latter is electrically conpport 7- atone end as 10, and atthe o posits end as 11, to a lever or spring mem er12, having also a contact point at its'end 13. The latter is adapted tonormally electrically communicate. with the circuit wire 14, and themember 12 is in electrical connection with the circuit wire 15.

Specification of Letters Patent.

' device such as is set forth in the switch is,

- heatin Patented Oct. 11, 1921.

Application men December, 1919. Serial in. 347,135.

The wires 5, 14 and 15 may be of any length required and are connectedthrough a 0 my above mentloned applications and diagrammatically shownherewith in the figure, and wherein the switch blades 16, 17 are ada tedto close, or interrupt the circuit from t e mam leads 19, 18 throughsuitable operating connections. The position of closure, however, ofsaid swltch blades being retained only at such time as the latch member20 is in its down or restrained position due to the contracted conditionof the expansible-wire 21.

.It will be Seen that when .the switch blades 16 and 17 respectivelycross-connect the wires 19, 5 and 14,18, and are held in such contactby'the latch member 20, wires 17, 14, .13, 9, 7 6, 4, 5, 16, 19, formthe path of current flow that will energize the heating coil 4 and alsothe thermal wire 9 in series therewith, that there is much lessflowthrough the wire 21 during the time that the thermal wire 9 iscontracted and contact made at the point 13, but upon the expansion ofthe wire 9 due to its heat not bemg dissipated with suflicient rapiditythere will be a breaking .of the circuit at 13, causing the entirecurrent which passes through the coil 4 tothe wire" 9 to also be passedthrong the thermal wire 21 in the remote device. This will setup acorresponding increase inr-temperature therein and coincident' therewithits ex ansion and the releaseof the'latch 20 an of the switch blade-17,' and its connected or associate switch blade 16, and a snapping ofthe" switch blades intothe position 25, 22. This is accomplished bysuitable spring connections and as indicated in the above entitledcopending applications.

e operation is as follows:

To operate the heater the switch blades 17, 16 .are thrown into the fullline position indicated, at which point they are automatically retainedby the latch 20. If for any reason it is desired to turn the heater ofl,they are thrown into the dotted positions 23, 24, and'may be turned onand oil as often as desired from the positions 16, 17 to 23, 24,or viceversa.

When in full line position the heating coil 4 will be energized bycurrent flowing through the leads 5 and 14, the water flowing from 2around the coil 4, the thermal wire 9 and; out through the outlet 3 willbe heated due to the electrical resistance of the parts within theheater casin 1. water in transit will extract the heat from the thermalwire 9 at a rate. sufiicient to keep its temperature lower than would bethe case if the circulating water was-stationary, or absent, thereforeany interruption in the flow of the water, or in case of itsboiling awayfrom the upper part of the casing 1, will'result in the wlre 9 becomingexcessively hot and coincident therewith its ex ansion and aninterruption of the circult between 14 and 12 at the contact point 13.This will throw the entire current through the thermal wire 21 causingits expansion, which releases the latch 20 and causes the switch blades16, 17 to snap into the positions 25, 22 thereby interruping the currentthrough the heating coil 4 and other parts and protecting them from anydamset my hand at the city and county of San age clue to excess heating,or excesscurrent flow.

I claim:

l. A method of electric thermal control This consisting of energizing aterminal device through two parallel paths and a return, one of saidpaths adapted to be interrupted on an excess of heat in said terminaldevice whereby a greater current is caused to flow over the other pathto thereby cause in a remote device in said other ath actuation torelease a spring actuate switch to open the energizing circuit. 1

2. A method of electric thermal control consisting of energizing aterminal device partly throughan expansion element adapted to release aswitch when an excess of current flows therethrough and gartly through alead paralleled thereto an said terminal device including tin-expansionelementadapted to break the circuit through said lead when said terminalelement exceeds a predetermined tem rature.

In testimony whereof, have hereunto Francisco, California.

MILTON H. SHOENBERG.

